1. Field of the Invention
The present invention relates to an image fixing device usable with a recording apparatus such as electrophotographic apparatus, electrostatic recording apparatus and the like, more particularly to an image fixing device wherein the possible offset of the material to be fixed is reduced or prevented effectively, the offset occurring to a rotatable member which is used for heating, pressing or heating and pressing, the material to be fixed in order to fix an unfixed image on a recording material.
2. Description of the Prior Art
In order to fix an image on a plain paper, an image forming apparatus widely uses a combination of a fixing roller and a pressing roller forming a nip therebetween.
This type of fixing device involves a problem that triboelectric charge is produced by the contacts between the plain paper and the rollers and between the rollers with the result of the plain paper winding or twining about the surfaces of rollers.
To solve this problem, Japanese Utility Model Application Publication No. 41793/1982 and Japanese patent application laid open under No. 143474/1981 propose that a charge removing brush is simply contacted to a roller surface, and that an alternating current is applied to the roller via a charge removing brush, respectively.
When those are put into practice, however, the ends of the charge removing brushes are stained by toner particles and paper dust with use so that the function of the charge removal is rapidly degrated. In other words, the function is so easily influenced by the period of use that the durability is not satisfactory.
It is true that the charge removal of those conventional devices is effective, to some extent, to prevent the twining or winding, of the recording material, about the rollers. However, the toner offset to the roller can not be satisfactorily prevented, because the charge removal function quickly decreases, which leads to the occurrence of offset toner which cannot be removed therefrom by a roller cleaner (blade or felt).
Since the triboelectric charge increases with the amount and speed of plain paper or recording material passing through the nip, the method or device lacking the durability is not practical.